Field
Coordination of interference handling may be beneficial in a variety of communication systems. In particular, enhanced inter-cell interference coordination may benefit from proper configuration and setup, as well as termination, of partnerships amongst base stations.
Description of the Related Art
In a conventional wireless communications network, base stations communicate with user equipment (UE) by radio frequency (RF). When the coverage area of two base stations overlap and when those base stations are using the same frequency then there is the potential for interference. The Third Generation Partnership Project (3GPP) has developed standards for enhanced inter-cell interference coordination (eICIC). To implement eICIC, a victim cell can send an X2AP: Load Information message to an aggressor cell with an Invoke Indication. The aggressor cell can then initiate resource status reporting with the victim cell such that the victim cell periodically sends X2AP: Resource Status Update messages to the aggressor cell. The aggressor cell can then minimize RF transmissions in subframes called Almost Blank Subframes (ABS). The aggressor cell can inform the victim cell which subframes are ABS using the X2AP: Load Information message.
The 3GPP standard indicates in 3GPP technical specification (TS) 36.300 (V10.11.0), section 16.1.5.2.2 “OAM may configure association between eNBs to use the time-domain inter-cell interference coordination.” So if an association is configured on each eNB indicating eICIC partnership pairs then the following scenario can occur.
A micro eNB 1 cell 1 can be configured with the eNB ID and cell ID of its macro cell eICIC partner. The partner can be eNB 2 cell 1. The macro eNB 2 cell 1 can be configured with eICIC partner cells including eNB 1 cell 1.
The micro eNB can looks up in its database its partner eNB and cell. The micro eNB can send an X2AP: LOAD INFORMATION message to the macro eNB. This message can indicate the cell ID of the micro (Cell Information Item>>Cell ID IE). The message also contains the Invoke Indication IE set to ABS Information. The X2AP: LOAD INFORMATION message does not have an IE to indicate the macro partner cell.
Upon reception of the X2AP: LOAD INFORMATION message, the macro eNB 2 looks up in its database the pair of eICIC partner cells that includes eNB 1 cell 1 and determines that its own cell 1 is the eICIC partner of eNB1 cell 1.
At that point, eNB 2 can then send an X2AP: LOAD INFORMATION message to eNB 1 with the current ABS pattern for eNB 2 cell 1. Further, eNB 2 can initiate resource status reporting from its partner cell by sending an X2AP: RESOURCE STATUS REQUEST message to eNB 1 cell 1.
This scenario requires that eICIC partnership pairs are configured at both the macro and micro eNBs. This requires more effort than configuration on either the macro side only or the micro side only. It is also subject to errors if the eICIC partnership pairs are inconsistently configured.
There are other X2AP messages that have information elements (IEs) that identify both the cell ID of the cell sending the message and the cell ID of the cell receiving the message. The X2AP: MOBILITY CHANGE REQUEST is an example of such a message. However, there is conventionally no approach to utilizing such messages to overcome the limitations found in the above scenario.